LEXUS LS430 2003 Factory Repair Manual

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Fig. 23: Chapter 2 Problem Symptoms Table (2 Of 2)

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TERMINALS OF ECM
1.ECM
Fig. 24: Identifying ECM Connector Terminals

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HINT:
Each ECM terminal's standard voltage is shown in the table below.
In the table, first follow the information under "Condition". Look under "Symbols (Terminal No.)" for the
terminals to inspected. The standard voltage between the terminals is shown under "Specific Condition".
Use the illustration above as a reference for the ECM terminals.

Fig. 25: Identifying ECM Terminals Reference Chart
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Waveform 1
Fig. 26: Identifying Waveform 1

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Reference:
WAVEFORM 1 REFERENCE TABLE
Waveform 2
TerminalSLT+ - SLT-
Tool setting5V/DIV, 1ms/DIV
Vehicle conditionEngine idle speed

Fig. 27: Identifying Waveform 2
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Reference:
WAVEFORM 2 REFERENCE TABLE
Waveform 3
TerminalSLU+ - SLU-
Tool setting5V/DIV, 1ms/DIV
Vehicle condition5th (lock-up) or 6th (lock-up) gear

Fig. 28: Identifying Waveform 3
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Reference:
WAVEFORM 3 REFERENCE TABLE
Waveform 4
TerminalSL2+ - SL2-
Tool setting5V/DIV, 1ms/DIV
Vehicle conditionEngine idle speed

Fig. 29: Identifying Waveform 4
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Reference:
WAVEFORM 4 REFERENCE TABLE
Waveform 5
TerminalSL1+ - SL1-
Tool setting5V/DIV, 1ms/DIV
Vehicle condition5th or 6th gear

Fig. 30: Identifying Waveform 5
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Reference:
WAVEFORM 5 REFERENCE TABLE
Waveform 6
TerminalNT+ - NT-
Tool setting1V/DIV, 2ms/DIV
Vehicle conditionEngine idle speed (P or N position)

Fig. 31: Identifying Waveform 6
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Reference:
WAVEFORM 6 REFERENCE TABLE
DIAGNOSIS SYSTEM
DESCRIPTION
When troubleshooting On-Board Diagnostic (OBD II) vehicles, the vehicle must be connected to the OBD II
scan tool (complying with SAE J1987). Various data output from the vehicle's ECM can then be read.
OBD II regulations require that the vehicle's on-board computer illuminates the Malfunction Indicator Lamp
(MIL) on the instrument panel when the computer detects a malfunction in:
1. The emission control s
ystem/components
TerminalSP2+ - SP2-
Tool setting2V/DIV, 20ms/DIV
Vehicle conditionVehicle speed 20 km/h (12 mph)

2. The powertrain control components (which affect vehicle emissions)
3. The computer.
In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 are recorded in the
ECM memory. If the malfunction does not reoccur in 3 consecutive trips, the MIL turns off automatically but
the DTCs remain recorded in the ECM memory.
Fig. 32: Identifying Malfunction Indicator Lamp

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To check DTCs, connect the scan tool to the Data Link Connector 3 (DLC3) of the vehicle. The scan tool
displays DTCs, the freeze frame data and a variety of the engine data.